Electric converter.



G. I. ZIMMERMAN, DEGD. J. a. ZIMMERMAN, ADMINISTRATOR. ELECTRICCONVERTER.

APPLICATION FILED 0012.17, 1906.

Patented June 16,1914.

4 SHEETS-SHEET 1.

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C. I. ZIMMERMAN, DEUD. I. G. ZIMMERMAN, ADMINISTRATOR. ELECTRICCONVERTER.

APPLIGATION FILED 0O'I'.l7, 1906. I 1,099,960, Patented June 16,1914.

4 SHEETS-SHEET 2.

Witnesses.- /n ventor':

e170 2 Mme/"man, w; by w Wt 231 G. I. ZIMMERMAN, DBCD. J. G. ZIMMERMAN,ADMINISTRATOR. ELECTRIC CONVERTER.

APPLICATION FILED 0OT.17, 1906. 1,099,960, Patented June 16, 1914.

4 SHEETSSHEET 3.

Witnesses.-

/r/ ventor':

C/ r'enceZZ'mm/"Man b [v t G. I. ZIMMERMAN, DEGD. J. G. ZIMMERMAN,ADMINISTRATOR.

ELECTRIC CONVERTER. APPLICATION FILED 00T.17, 1906.

Patented June 16, 1914.

4 SHEETS-SHEET 4.

7 INVENTUH CLARENCE .Z. mMERA IAAL ATTY 'fication.

' TATES PATENT orrron.

cLA'nENcE IRVING zmMERMAN, or NIAGARA iliALLS, NEW YORK; JAMES e.ZIMMER- MAN, ADMINISTRATOR OF SAID CLARENCE I. ZIMMERMAN, IQECEASED,ASSIGNOB.

'ro enrtEBA -Emcr'mc COMPANY, A coRPon 'nouor NEW YORK.

- ELECTRIC CONVERTER.

' specification of Letters Patent. Patented June, 16, 1914;,

Application filed October 17, 1906. Serial No. 339,399.

To all whom it may concern Be it known that I, CLARENCE LZIMMER-.wr.-\X,'"a"citizen of the United States, residing atNiagara,Falls,--co1inty of Niagara, State of New York, have inventedcertain new and useful Improvements in Electric C011.- verters, of whichthe following is a speci- This invention relates to the conversion ofalternating current nto uni directional current or other- --fo1"mshaving special qualities applicable to various electrotechnical uses.

I have hereinafter described several distmct types of apparatus suitablefor carrying out my improved method, and although the separate typesvarlous specific characteristics, neverthe less, they all embody thebasic idea of my invention,

My system includes one or mOre asymmetric conductors together with meansfor plates immersed taining one accumulating a very appreciableelectrostatic charge. In thosespecies wherein I have used a mercuryvapor tube as an asymmetric conductor, I have combined with itanelectrostatic condenser of the ordinary type. In those species in whichan electrolytic asymmetric conductor is used, I make use of thepeculiar, electrostatic capacity of the asymmetric conductor itself,thus, ina sense, combining the condenser in a single unit. I am awarethat mention has heretofore been made of the electrostatic capacity ofanelectrolytic cell consisting of two aluminum in a suitable electrolyte.I am also aware that electrolytic cells conaluminum electrode and onecarbon or iron electrode have been used for. the rectificationof'current. I am not aware, however, that it has ever been proposed toutilize simultaneously the rectifying and electrostatic *properties ofsuch cells, particularly when disposed in such systems as arehereinafter described.

According to my improved method of rec-'- tificatlon, the alternating;current maybe converted into uni-directional current,

' cithersteady or pulsating, and this unidi' rectional current may haveavoltage higher age.

are distinguishable by- "than that of the original alternating current.In fact, :according to some of the species hereinafter described, tionalvoltage may be several times higher than the original alternatingcurrent volt- So far aS'I amaware, this resultis broadly new 4 As-Willappear tailed description,

instead of simple rectification, a condenser is so connected that itacts to boost the volt+ age at the load circuit, the entire system be:ing such that by changing the connections for the load circuit, thecondenser may be used to equalize the load potential instead of boostingit,

a part of this specification, grammatic representation of asimple formof. rectifier using a mercury vapor asymmetric conductor and anelectrostatic condenser of the usual type. Fig. 2' ives a similar systemutilizingltwo vapor tu es and a condenser. Fig. 3 illustrates a. systemsimilar to that of Fig. 1, except that the rectified current is ofpositive polarity at the central or intermediate terminal. Fig. 4corresponds to Fig. 2 except that by a reversal of the asymmetricconductors, the polarity of the rectified current is reversed. Fig 5 isa diagrammatic representation of a system in which he electrostaticcondenser and asym:

of the systems shown in Figs. 1 and 3, .the"

What I choose to term a former illustrating negative rectifier and thelatter a positive rectifier. A 8 shows a system in which three vaporamps orvalves are utilized in connection with two large electrostaticcondensers'toyield direct current of from the followingdc the system of.my presentv ,IIIVQntlOIl is a rectifying system in which,

In the drawingsannexed to and forming- Figure 1 is a di'a.-

the uni-direcsubstantially constant voltage.v Fig. 9 shows a systeminwhich three electrolytic cells'are V Fig. 10, showsan arrangement forincreasing still further the diflerence. between the potential of thedirect current output and the alternating current input. This differs"from the arrangement of Fig. 9 by the inany appreciable current in the.electrical potentials between. various having an aluminum electrode, i

clusion of a second electrolytic condenser connected between the directcurrent terminals. Fig. l1--shows a new type of asym-.

metric conductor, and illustrates its use in a system of rectification.Fig. 12 illustrat% a polyphase-system for producing and utilizing arotating electrostatic charge. 13, 14:, '15, 16 and 17 are curvesillustrating parts of the systems shown in the other figures.

In several figures of the drawing. Ihave illustrated a mercury vaportube orlamp as an asymmetric conductor or valve to transmit current inone direction and to prevent the flow of currentin the oppositedirection. Such a tube or lamp may consist, as illustrated in Fig;provided with an anode 2 of solid material, and a vaporizable cathode 3of mercury. A second or auxiliary anode 4 is also'provided and issupplied with current from a battery 5 or other source of energy, forthe purpose of maintaining a continuous are from the mercury cathode 3.This auxiliary arc, or

side branch, serves to maintainthe' tube in such a condition that itwill transmit current tending to flow from the solid anode 2 to themercury cathode 3, but will. prevent current flow in the oppositedirection. The

valve-like action of a mercury vapor tube is.

also present in an electrolytic cell of the type combination with anelectrode of inert ma erial, such as carbon, platinum or iron, and anelectrolyte capable .of developing an insulating coating on or about thealuminum elect-rode. Such a cell will transmit current readily from theinert or carbon electrode to the aluminum electrode, but will. nottransmit opposite direction. Probably this asymmetric action is due tothe formation of -a coating of oxid, hydroxid or other material on thealuminum plate, this'coating being of extreme .thinness and highresistance. These properties of an aluminum electrolytic cell are wellknown. r

In addition to the asymmetric property of an aluminum cell, I find thatby proper disposition of the electrodes, at veryappreciable'electrostatic capacity may be obtained,

. and furthermore, that the condenser action of the cell may be utilizedin connection Figs.

1, of, an mclosing envelop 1 I with the other elements here shown, for

the rectification of alternating current, and for its conversion intounidirectional current of pulsating character or into current ofsubstantially constant potential. According to my invention advantage istaken of the properties of an electrolytic cell, of combining in itselfboth the properties of an asymmetric conductor and the properties of acondenser, and this dual role which the electrolytic cell is able toplay, I may take advantage of by substituting an electrolytic cell inplace of a vapor 'tube and a tinfoil condenser in] the system hereindisclosed and claimed.

In the following detailed description of my invention, I haveillustrated species utilizing vapor :electric'valves, and other speciesusing electrolytic valves, and in those systems using vapor electricvalves I have an ranged tin foil or similar condensers in those parts ofthe circuits,requiring electrostatic capacity, while in the systemsutilizing electrolytic valves I have relied on the electrolytic. cellitself to supply the neces- 'sary capacity. It should be understood thatthe illustrations of electrolytic cells shown in the drawings are merelydiagrammatic, and that in practice I could increase the eler trostaticcapacity by increasing the area of the aluminum electrode in anysuitable way.

Fig. 1 illustrates a system of rectification, and comprises, in additionto the vapor elec tric device heretofore described, an electrostaticcondenser 6 of the tin foil or other well known type, and an alternatingcurrent source, such as a transformer having a primary-7 and a secondary8. The cathode 3 of the vapor tube is connected to one of the leads 9 ofthe transformer secondary and a condenser 6 is connected between theanode 2 of the vapor tube and the other lead 10 of the alternatingcurrent source.

rThe' condenser 6 is preferably large enough in capacity to permit anappreciable flow of current from the transformer main 10 through thevapor tubeto the other terminal of the transformer. As current cannotflow back through the vapor tube to equalize the charge in condenser 6when the potential of the source reverses, there re sults a negativecharge on the conductor connecting the condenser to the vapor tube, thischarge establishing a potential across the conductor terminals equal tothe maximum potential across the transformer secondary 8 less the dropin the rectifying arc tube. readily apparent upon consideration of theflow of current out of the condenser when the transformer lead-1Obecomes positive, and the absence of return current when that leadbecomes negative. As lead 10 becomes positive, it communicates apositive char e to one side of condenser 6, and thereby in uces Thatthis value is correct will be may be relatively small say to volts,

and the voltage of the source may be as high as several thousand voltsthe condenser receives substantially the maximum the transformersecondary and that pothe conpotential of 1 takes up a chargecorresponding to tential. When the source reverses,

- denser is prevented from discharge by the by connecting thesubstantially double ,mum

.to terminal 13'.

valve-like action of the vapor tube, and

tends to maintain across its terminals a constant potential equal tothat of the maximum value developed by the alternating current source.After the first cycle of the alternating current source, the condenserconnected as above described neither charges nor discharges butmaintains a definite steady voltage across its terminals. If, now, meansare*provided for taking ofi a small partof this charge, .the energy sotaken off will-be substantially constant -potential and at a voltageequal to the maxipressure of the alternating current supply less thedrop in the rectifier tube. For conveniently utilizing this charge, Ihave provided the transformer terminals 9 and 10 with terminals 11 and12, and; I have connected a'third terminal 13 to the conductorconnecting the condenser 6 to anode 2 of the vapor tube. Translatingdevices such as lamps, motors, etc., connected between terminals 12 and13 will receive uni-directional current of substantially constant.voltage, the current passing through the translating devices fromterminal' 12 It should, of course, be understood that thecapacity ofcondenser 6 must be made large enough to supply the desired energy tothe translating devices without great loss charge, as otherwise, willreceive pulsating current the translating devices instead of constantpotential current.

'My system of rectification provides not only for the production ofconstant potential direct current as above described, but also for theproduction of directional current. This may be obtained translatingdevice between the terminals 11 and 13, the terminal 11 being positiveand the terminal. 13 being negative. Between these terminals thepotential periodically varies from zero to practically twice the-voltageof the transformer secondary, for when terminal 11 is at -its maximumnegative value, terminal 13 is at substantially 'the same potential, butwhen the polarityof the-source reverses, the condenser and source act'inseries toqdevelop potential across the terminals 11 and 13-, and thusmake this doublepotential available to perform useto cut the wiresbetween ing operation in the potential of the pulsating uniful work. Inpractice, it sometimes happens that this maximum potential falls alittle below the calculated value because of irregularity in the waveshape of the transformer current and because of leakage in tube, personsskilled in the art, and which need not be referred to except as sourcesof the slight discrepancies which may arise be- -7o i the condenser andvoltage drop in the vapor factors which are well understood by v tweenthe theoretical values of the voltages and the values obtained inpractice. These difierences are mainly of theoretical interest and willnot be further discussed herein.

A somewhat homely explanation of the double potential availablemomentarily between terminal 11 and 13 may be made as follows: Assumingthat the condenser (i is receiving its'charge, the potential at itsterminals will rise to substantially that of the transformer secondary 8(neglecting the ipoltage drop in the :tube) then if we were thecondenser and transformer before the potential had time tore-verse, wewould have stored in the condenser -a charge, the voltage of which isconstant and equal to the maximum'instantaneous voltage of thetransformer secondary. Then let us assume that the transformer voltagereverses in polarity and after that reversal is complete, we connect thecondenser with the secondary, in such a way that it serves to boost thevoltage of the secondary. This will give a voltage between the freeterminal of the secondary, substantially double that originallyimpressed on the condenser, the effective current supplysource acting inseries with the transformer second 8 between points 11- and 13. Butinstead of by hand rectifier of the present system doesit for us.

,At each half wave it connectsthe condenser for a charge and -at thesubsequent half wave it disconnects the condenser at one end leaving itconnected in at the other end in such a way that it boosts the reversedvoltage of the transformer secondary.

For a better understanding of the poten-. tial difierences betweenvarious parts of the system described, reference may be had to Fig. 13in which these difierences are graphically illustrated. Let itbe assumedthat the horizontal line 13 is a curve representing the potential at theterminal 13 in Fig. 1 and that vertical distances above being thecondenser 6- performing this connecting and disconnectas above assumed,the

this line are positive potentials with respect For purposesof'discussion, the terminal 13 may be considered as at earth otential.When the condenser of Fig. 1 has been charged to its maximum voltage,the potential of terminal 12 will be positive with respect to terminal13 by an amount equal to the maximum momentary difference to terminal13.

12 and 13. Of these two terminals 12 is positivewith respectto-13iSimilarly the.

. vertical distance between curves 11' and 13 at any particular pointoftime represents the instantaneous potential on open circuit betweenterminalll and terminal 13. Thus at the instant of time marked A,B, ter-.minal 11 is'at its maximum positive value with respect to termil l qll2and'is at twice this value with respect to terminal 13. B

following along the curve to the instant marked O-D, it will be seenthat terminal 11 drops to the potential of terminal 13, so that inpassing from A-B to CD it drops to zero from a maximum equal to twicethe maximum instantaneous difference of potential between 11 and 12, orin-other -words twice the maximum instantaneous voltage of thealternating current source.

ltswill be understood that when the load current is small with respectto the capacity of the condenser the curves of Fig. '13 will besubstantially accurate for illustrating voltage available at therespective terminals for sending current through the load. If the loadcurrent is so heavy as to, pull down on the condenser voltage at-eachdischarge thereof, the wave shapes illustrated in Fig. 13 will beflattened out and modified somewhat, as will be readily understood.

Fig. 2 illustrates a transformer 14'and vapor tubes 15 and 16 connectedrespectively to the transformer terminals in such a way as to permitcurrent to flow from either terminal to a binding post 17 which therebybecomes a positive terminal of the consumption circuit. A condenser 18of relatively high'electnostatic capacity is connected in shunt withvapor tube 16. The transformer secondary terminals are connecteddirectly to bindingposts 20-and 21, from which connections may be madeto the positive terminal 17 through the loads 22 and 23. When thepolarity of the transformer secondary is such as to send current fromanode to cathode in the vapor tube 15, a posltive charge is introducedon plates 24 and a similar inductive charge is induced on the opposingplates 25. A charge so Imprisoned cannot escape through the vapordevices 13 and 16 because of their asymmetric action, and can only passoff by way it being understoodthat the condenser is of ample capacitywith respect to the resistances of the load circuit. If the load isconnected at 22 instead of at 23 the charge of condenser 18 will passfrom terminal 17 to terminal 20 and will be at substantially double thevoltage of the transformer secondary, because of the fact that underthese conditions, the condenser voltage is added to that of thetransformer secondary or in other words the condenser boosts thetransformer voltage. In addition tothe energy transmitted from terminal'17 to terminal 20 by way' of condenser 18, a certain amount is also.

transmitted directly from the source by way of vapor'tube'16, and thislatter energy 1s,

of course, at the potential of the transformer secondary.

Fig. 14 illustrates graphically the instantaneous differences ofpotential between the terminals 17, 20 and 21 when no current is beingused in .the load circuits-22 and 23. For convenience of reference, theterminal 21 has been considered at zero potential and therefore capableof representation by the horizontal line 21 shown in Fig. lir -V1111this as a datum line the instantaneous values of the terminal 17 areproperly represented by a parallel straight line 17 separated from theline 21 by. a distance corresponding to the maximum difference ofpotential of the alternating current source. Terminal 17 is alwayspositive with respect t terminal 21 and consequently line 17' apearsabove line 21. The potential diference between the. terminal 21 and theterminal 20 is properly represented by a sine curve 20 symmetricallydisposed. with respect to the line 21'.

From an inspection ofFig.. 14 itwill be seen that underthe condition ofno load the ioo terminal 17 is at a constant potential above theterminal 21 equal to the maximum impressed voltage of the alternatingsource, and that it is at a potential above the terminal 20 by apotential which periodically varies from zero to substantially twice theimpressed maximum voltage. This high voltage is of course producedbycharging the condenser 18 in parallel with the source and dischargingit in series therewith. Although the curves shown in Fig. 14 properlyillustrate the potential difference of the terminals under conditions ofno load, they are not, unless the large condenser 18 be considered ofinfinite capacity, strictly accurate for a loaded system. If thecondenser is notlarge or if the demands on it are heavy, the storedenergy may be exhausted suiiiciently to give a illustrateddiagrammatically in Fig. 15, as-

suming that either or both of the loads 22 and 23 are connected in.

From an inspection of Fig. it will be seen that the partial exhaustionof the condenser causes ,a slight droop in curve 17'. This means adecrease in the voltage on the load until curve 17 intersects thecharging potential 20. Then the voltage on the load.

and the voltage across the condenser go up together and thecondenserstarts off with a causes a rapid falling off the curve. 17 will notnew'charge.

If the system shown in Fig. 2 be overloaded, the, exhaustion of thecondenser in the potential of the terminal 17 at complete exhaustion thecurve 17 intersects the curve 21. words, the terminals 17 and 21- reachthe same potential. It happens, however, that cross the curve 21, for

further demands of the load 22 are supplied by energy passing directlythrough vapor device 16 to the terminal 17. This vapor device thereforeperforms an important function "in preventing from charging up with-thewrong polarity in case of an excessive demand in the load circuit 22. l

Fig. 3 shows a system in many respects similar to that of Fig. 1, anddifieri'ngprincipally in the fact that the asymmetric conductor 26 isreversed, or in other words, is

connected to the transformer secondary by itsanode-lead instead of byits cathodelead. This makes the conductor 27 joining the condenser andvapor tube positive with respect to the transformer terminals 28,

The electrolyte being once charged negatively remains in that conditionuntil equilibrium 29 but otherwise the voltage relations aresubstantially the same as that of the system shown in Fig. 1. Forconvenience in description, the system shown in Fig. I may be termed anegative rectifier, and the system of Fig. 3 may be termed a positiverectifier, and these terms are hereinafter used to describe elements ofsystems in which these positive and negative devices are combined tocooperate as for instance in Fig. 7.

Fig. 4 shows a system difi'eri-ng from that of Fig. 2 by a reversal ofthe asymmetric conductors to render the intermediate terminal negativeinstead of positive. To secure this result the vapor tubes 30 and 31'havetheir anodes connected directly to the intermediate conductor orterminal 32, and their cathodes connected respectively to thetransformer mains 33 and 34 and the corresponding load terminals 35 and36. The condenser 38 is connected in shunt with one of the tubes in thesame way that condenser 18 of Fig. 2 is in shunt with its tube'16.

Fig. 5 illustrates my invention as embodied in an electrolyticasymmetricpconductor of the aluminum type. The system is noticeable dropin the In other the condenser 18 'tive,

.no opposition to he made up of a source-lot alternating current 39'connected directly to load terminals 40 and 41-. Across these terminalsis connected an electrolytic cell 42 comprising a small aluminum plate43 and a large aluminum electrode 44, an electrolyte 45 of the charactercommonly used in aluminum-asymmetric conductors, an inert electrode 46of carbon, iron or platinum, connected to an intermediate load terminal47. In practice, I make electrode 44 of large area and capable ofholding a'high electrostatic charge, and I make the smaller electrode 43of such small size that it possesses'little or no electrostaticcapacity. I consider that the electrostatic capacity of an aluminumelectrode is comparable to that of an ordinary tin foil condenser, andthat the aluminum plate is one armature of the condenser, theelectrolytethe other armature, and the insulating. fihn or coating on the aluminumplate is the dielectric. For a complete understandingof my invention asembodiedin apparatus of the type illustrated in Fig. -5, it should'benoted that the electrolytic cell is a rectifier as well as a condenser:'When the polarity of the source is such that terminal 41 is posiapositive charge is communicated to the aluminum plate 44, as onearmatureof a condenser, and a corresponding negative charge is inducedin the electrolyte 45, it being understood that this phenomenon 183C-companied by a flow of current from the electrolyte and the smallaluminum electrode 43. The laiter opposes substantially flow of currentfrom the electrolyte to the plate, although it does zoppose apractically prohibitive resistance to a flow of current in .the oppositedirection.

;is restored through some other path. than ;that furnished by thealuminum electrode since current can never flow directly from thealuminum to the electrolyte. If, now, a

circuit is completed between terminals 41 and 47 or between 40 and 47 sothat energy can enter the cell .by way of the inert electrode 46, thenthe condenser will tend to discharge and produce equilibrium between theelectrolyte and the metal ofplate 44. If the condenser is of-sufficientcapacity with respect to the return or load circuit between,

say' terminals 41 and 47, then the condenser will maintain auni-directional current of substantially constant potential in this loadcircuit, and together with the rectifying action of the small aluminumelectrode, will serve to convert the alternating current of the sourceinto direct current for use between terminals 41 and 47. If the externalcircuit is completed by connecting the load between terminals 40 and 47,then the condenser acts in series with the source to boost the voltageto substantially twice that of the source, excluding, of course, theGIL, and leakage losses in the cell itself. The output is unidirectionaland pulsating. The entire system of Fig. 5 is comp-arable to that ofFig. 1, and' since the intermediate terminal 47 is negative, I choose toterm the device, as a whole, a negatlve rectifier.

.As contrasted with the negative rectifierof Fig. 5, I have shown inFig. 6 a positive electrolytic rectifier for producing effect thedesired results. With the arrangement as described, the intermediateterminal 55 is positive with respect to terminals 49 and 50, and theelectro-motive force between 55 and 50 is substantially constant andequal to .the maximum value of the alternating current source, while thevoltage between 55 and 49 is pulsating and reaches a maximum valueapproximately twice the maximum of the source.

In all of the modifications above described,

\ j the maximum steady voltage of the rectified current'has-beensubstantially equal to the maximum alternating current pressure, but

in the systems I am now about to describe, the pressure available is twoand even three times the maximum value of the alternating currentsource. This effect is produced by combining whatI have termed positiverectifiers with negative rectifiers in such a way that their effects arecumulative. The principle involved is broadly applicable to anyasymmetric circuit in combination with one or more electrostaticcondensers.

By combining the negative rectifier of Fig. 1 with the positiverectifier of Fig. 3,

I'obtain the system shown in Fig. 7. One rectifier 56, has its cathodeconnected to the main of the source, and its anode connected through acondenser 57 to the opposite transformer-main. The other vapor tube 58has its anode connected directly to the transformer secondary and itscathode connected through the condenser 59 to the opposite terminal ofthe source. The junction between vapor tube 56 and condenser 57 isalways at negative potential, while the junction between rectifier 58and'condenser 59 is always at positive potential, and the load 60connected between these junctions is traversed by a unidirectionalcurrent of substantially constant potentiahthis potential being approximatelv twice the maximum value of'the alternating current source. Myinvention will be readily understood if it is noted that the condensers57 and 59 are charged in parallel and discharged in series.

Fig. 8 shows a system in which three vapor tubes are utilized asasymmetric conductors. Two of the tubes, 61 and 62, have theiranodes'connected to a common terminal" 63, and their cathodes connectedrespectively to the alternating current mains 64 and 65. Tube 61 isshunted by condenser 66 of relatively large electrostatic capacity.These elements constitute a negative rectifier and serve to keep theterminal 63 at a constant negative potential with respect to thealternating current main 64. Combined with this negative rectifier is apositive rec-- tifier consisting of a vapor tube 68, having its mainanodes 69, and 70, connected respectivelyto the line conductors 64 and65, and its cathode connected to a load terminal 71. Condenser 73 isconnected between load terminal 71 and the alternating current main 65.This positive rectifier serves to keep the load terminal 71 at apositive and con.- stant potential with respect to the alternat;- ingcurrent main 65. If theload 74 is con} nected between the chargedterminals 63 and 71 current will flow from the terminal 71 to 63, andthe voltage-of the energy transmitted will be the resultant of the twocondensers discharging in series combined with'the energy delivereddirectly from the alternating, current source by way of the'vapor tubes.In other words, the unidirectional current delivered is the resultant ofan alternating current having substantially the potential-of thealternating current source, and a direct 'current having substantiallydouble the maximum voltage of the alternating current source. Theaverage value of the resultant is twice the maximum value of thealternatlng pressure wave. The efiective value is the vector sum of thisaverage value and the value of the alternating pressure wave; themaximum value is three times the maximum value of the alternatingpressure wave; the minimum value is equal to the maximumof thealternating pressure wave. In these calculations the voltage drop in theasymmetric conductors and the leakage and other; losses in thecondensers, have of course, been excluded. It will be understood thatthe condensers 66 and 73 must be properly proport-ioned with respect tothe load in order that the condenser voltage may not drop ofi abnormallywhen the load circuit is closed.

For a better understanding of the potential difference between thevarious parts of the system, reference may be had to Fig. 17. Forconvenience of reference, the terminal 63 is taken as the point of zeropotential and all other parts of the system are referred thereto. Thepropriety of this assumption will be apparent when it is considered thatterminal 63 might be grounded and thus placed at zero potential withre-' alternatmg supply source. This constant.

voltagedlfi'erence is of course maintained by the storing and restoringaction of condenser 66. The supply lead 65 variesin potential withrespect to conductor 64 in a simusoidal relation, as illustrated by thecurve 65. Conductor 65 is separated frombinding post 71 by a condenserof large capacity and therefore binding post 71 is at constant potentialfrom conductor 65, as illustrated by curve'71.

From an inspection of'Fig. 17 it will be seen that the maximumdifference of potential between. binding post 63 and binding post '71corresponds to the maximum dispress it differently,

tance between curve 71 and curve 63 and is equal to three times themaximum impressed voltage of the system. The minimum dif ference ofpotential between these binding posts equals one times the maximum ofthe system. The load potential is composed of three components; twouniform and equal potentials, and the alternating current source itself,all acting in series. To exthe pressure between the terminals 71 and 63is composed of two equal uni-directional pressures with analternatingpressure superimposed upon them.

As previously stated,-the potential differencebetween terminals 71 and63 attains a maximum three times the maximum of the alternating currenttransformer voltage, and .then drops to 'a value equal to only one timesthe maximum potential value of the transformer. In order therefore toobtain a uniform or practically uniform difference of potential equal tothree times the maximum value of the transformer voltage, it is onlynecessary to store energy during the peak of the'pulsating energy.

Fig. 9 shows an .electrolytic system in many respects analo ous to thevapor tube system of Fig. 8. W0 electrolytic asymmetric. con'ductors 75and 76 have their inert or iron electrodes 77 and 78 connectedrespectively tothe alternating current mains 79 and 80.' Cell 75isprovided with an aluminum electrode'81 of negligible electro staticcapacity, and this is. connected directly to the load terminal 82 andalso to the aluminum electrode 83 of the other electrolytic cell. ,Thislast named electrode has a large surfacearea and is-intended to have avery appreciable electrostatic capacity. The apparatus just describedconstitutes a positive rectifier, and maintains,-ortends to maintain theload terminal 82 at positive 83, and by current main 80. The negativerectifier of the system consists of a single cell'8a provided with alarge aluminum electrode 85 and a smaller aluminum electrode 86, thiscombination serving to keep the load terminal'87 at a constant andnegative potential with respect to the alternating current main 79 Whenthe alternating current main 79 is positive, current flows throughcell-75. from anode 77 to aluminum electrode 81 and thus brings the loadterminal 82 to positive potential and charges condenser 7.6.Simultaneously a positive charge is transmitted to the large aluminumplate potential with respect to the alternating of cell 84, and thisrenders the electrolyte and load terminal 87 negative by driving currentthrough the small aluminumplate 86 to the other load terminal. Thisnegative charge cannot escape when the potential of the main 79 dropsback to zero, and consequently, acts in conjunction with the positivecharge on the opposite terminal to force current throughany loadconnected between these terminals. The voltage of the currentdischargeis the resultant of the combined action of the condensers and thealternating current source.

' When the polarity reverses and the conductor 79 becomes negative,current can flow from conductor 80 through cell 76 to electrode 83 andthen through the load which connects 82 and 87, and on through cell'84to electrode 85. The voltage of the transformer, when thus applied tothe load through the two electrolytic cells, is boosted by the condensercharge held at electrode the condenser charge at electrode 85, and it isthis boosting of the transformer voltage which'gives to the .loadcircuit between 82 and 87 a maximum voltage substantially three timesthat of the maximum instantaneous voltage of the transformer. Whileconductor 80 is positive, current cannot leave electrode 86 because itis of aluminum, and, likewise, current cannot leave electrode 81, theseelectrodes being cut off by their insulating films as soon as thepolarity of the transformer reverses.

Fig. 10 shows a combination of cells simi-,- lar to that of Fig. 9, butwith the addition of a cell 88 placed between load terminals 89 and 90.This cell has two opposed alumiup energy and smooth out the pulsationsof the unidirectional current delivered to the load terminals 89 and90,-so that this pressure is uniform and higher in value than theaverage value of the pulsating current supplied the two terminals 89 and90. This result is effected by the condenser properties of the cellwhich insure its discharge at a ties.

pressure equal -to the maximum voltage of the pressure momentarilyimpressed on its terminals by the unidirectional pulsating pressuresupplied to electrodes 92 and 91. There is, then, a uniform staticcharge bound up in this cell 88 having a pressure which is theoreticallyequal to three times the maximum value of the alternating pres sure onthe circuit. Any receiving device, such as a consumption circuit 93placed across this cell 88, will be actuated by this triple voltage, andof course, will at the same time tend to lessen the uniformlty inproportion to the amount of energy drawn ofi. That there may be anavailable load potential equal to three times the impressed voltage willbe readily understood, when we consider that. the t o' condensers chargein parallel with the ource and then discharge in series with each otherand in series with the source. This gives a maximumyoltage three timesthe maximum impressed voltage. The charge may be continuously held atsubstantially this maximum value by the condenser Which shunts the load.

Fig. 11 shows a system equipped with an asymmetric conductor which, sofar as I am aware, possesses novel features and quali- The asymmetricconductor consists" of a refractory s ick 94 consisting of oxids of therare metals or of other .metals of that general nature heretoforeemployed in the so-called N ernst glowers. .Such materials aresubstantially non-conducting at ordinary temperatures and may easily berendered conductive by heating with a flame or in any other well knownmanner, and will thereafter transmit current and attain a brightincandescence. The glower is illustrated as provided wit-h the usualform of resistance ballast 95. I

I have discovered the important fact that such glowers not onlyemitlight but also emit energy of such a nature that it renders theadjacent space conductive for current. This conductive region extendsoutward for a distance of only a. few milli-meters from the incandescentglower. In fact, it is confined principally or wholly to the end of'theglower which is negative at the particular instant. Thus, if the gloweris operated on alternating current, the copductive region shifts fromone end of the glower to the other at each half-cycle, I o

In the drawing I have illustrated conductive plates or points 96 and'97held near the respective ends of the glower in such aposition as toreadily'transmit current across the gaps which are made conductive bythe current. As the result, the intermediate load terminal 98 ismaintained at a constant negative potential with respect to thealternating current 'main'99. The system is analogous to the vapor tubesystemhepetofore described and illustrated. in Fig. 4 difi'eringtherefrom only in the different character of the asymmetric conductorused.

Although I have above described my basic invention as applied tosingle-phase appason skilled in'the art that it isalso appli cable topoly-phase systems, and that many modifications and species will readilysug-' gest themselves. Although I have not deemed it expedient todescribe such polyphase systems at length, I have illustrated in F ig.12 one arrangement which possesses certain novel characteristics Theelectrolytic cell 100 is provided with three aluminum electrodes, 101,102 and 103 whichhave a large electrostatic capacity, and which areconnected to.onev terminal of a three phase source 104.. The neutral ofthe source is connected through a suitable consumption circuit 105 withan iron or carbon electrode 106, immersed in the electrolyte. Thealuminum electrodes cannot transmit current 1 to the electrolyte becauseof the protective action of the insulating films formed thereon by theelectrolyte, but they do have power to take up an electrostatic charge,and to render the electrolyte at an appreciable negative potential withrespect to the neutral of the three-phase source. As the result, currentwill flow from the neutral of f the source through the l'oadto theelectrolyte and then back to the source by way of the particularaluminum electrode,or electrodes which happen at the instant to be oftheproper polarity to receive the current.

In a single-phase electrolyte condenser,

the negative charge may be considered as sent back and forth from oneelectrode to the other, but in a poly-phase condenser as above describedthe negative electrostatic charge in the electrolyte shifts from oneelectrodeto the otherwith a speed corresponding to the frequency of thesource, and thus rotates in synchronism therewith. I contemplate the useof this rotating electro-. static, charge for various electrotechnicalapplications, andI have hereinafter indicated some of themathematicalrelations thereof.

The sum of the-coulomb charges on the three platesis constant, and isequal to the maximum charge capable of being held by the cell with agiven impressed pressure. This maximum charge does not collect at a timewhen the pressure across two of the plates is a maximum, as in case of asinglephase condenser, but it collects when two of the three plates areat an equal positive potential with respect to the third plate.

The constant coulomb charge is equal to cov /2E of one of the threesmaller plates, the delta alternating currentp' .where C is equal to theelectrostatic capacity nd' 1i 1 "is;

70 ratus, it will, of course, be obvious to a persaid asymmetricconductor.

pressed on the cell. The unidirectional and constant pressure set upbetween the electrolyte and the neutral point of the threephase circuitis theoretically equal to the maximum value of the star voltage of thecircuit. 7 I

If one of the three electrodes be disconnected from the circuit theconstant unidirectional pressure drops to pressure. The total energystored in the condenser is constant at all times, and is equal to whereC is the capacity of one of the plates and E is the delta pressureimpressed the cell.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,+

1. The combination with a source of alternating current, of a condenserconnected to receive energy therefrom, stationary means for preventingdeliverance of energy to said condenser during alternate half waves ofsaid source a load circuit and connections between said source, saidcondenser and said circuit, whereby a potential difl'erence greater thanthat of said source is applied to the circuit.

2. The combination with a source of alternating current, of a condenserreceiving energy therefrom, an asymmetric conductor connected in serieswith said condenser, and a unidirectional load circuit connected across3. The combination with absourc of alternating current, of a condenser,stationary means for deliver'ng energy to said condenser during eachalternate half wave of said source and for preventing the deliverance ofenergy thereto during the remaining half wave, and a loadcircuitrec'eiving energy by way of said condenser at a maximum potentialhigher than the maximum potential of said source.

l. The combination with a source of alternating current, of means foraccumulating an appreciable electrostatic charge, a load stationarymeans of negligible circuit, and

reactance for conducting said charge to said load as unidirectionalcurrent. v

5. The combination with alternating current mains, of an asymmetricconductor and means, for storing an electrostatic charge connectedacross said mains and tending to maintain a constant difference ofpotential across said storing means, and translating devices connected:to receive energy from said storing means by way of said alternatingcurrent mains.

6. The combination with alternating'current mains, ofa' condenser.connected to take energy therefrom, means for limiting the delivery ofenergy to said condenser, said means having greater conductivity in onedirection than in the other, and a translating rent mains, of aconductive path therebetween including a condenser, and a second pathcommon to a part of said conductive,

path and including translating devices, the places of connection forsaid translating devices being at parts of said conductive path having amaximum potential higher than the maximum potential across said.alternating current mains; Y

8. The combination of an alternating current source, anasymmetricconductor con nected to said source, "a condenser in circuittherewith,- and a load circuit receiving energy by way of said condenserat a potential higher than the maximum potential-of said alternatingcurrent source.

v 9. The combination with alternating current mains, of an asymmetricconductor, and means for storing an substantially the otential of saidsource, said conductor an storing means being connected across saidmains, and a load circuit connected across said asymmetric conductor.

electrostatic charge at '10. The combination of a source of alternatingcurrent, condensers for storing electric energy from said source in aplurality of places, asymmetric means for preventing the return ofsaid'energy to said source, and a load circuit connected to receive thestored energy from one of said condensers as a unidirectionalflowboosted in voltage by energy from another of said condensers.

In witness whereof, I have hereunto set my hand this 13th day ofOctober, 1906.

CLARENCE IRVING ZIMMERMAN.

Witnesses:

JESSIE B. MoVnAN, MICHAEL J. NOONAN.

I tori'cit'ions in Letters Pateiit No. 1,099,960;-

It it; hereby certifiefi that in Letters Patent No. 1,099,960, grantedJune 16., 1914, uponthe application of Clarence Irving Zimmerman, ofNiagara F ails, New York, for an improvement in Electric Converters,errors appear in the printed specification requiring correction asfollows: Page 3,- linei2el, before the word substantially -insert theord of} page 7, line li for the word simusoidai read sinusoidal; samepage, line 28, after the Word maximum insert the words impressed wltdge;and that the eaid Letters ]E "atent should be read with thesecorrections therein that 1 the samemay conform to the record 0f thecasein the Patent Ofiiee. v

Signed and sealed this 7th day of July, A 1)., 19 4.

R. F. WHITEHEAD, Aothzg Ummniasioner of Patents.

